FORT WORTH — A man convicted of killing a North Texas pastor caused various problems while jailed after his arrest for the crime — including assaulting jailers — and had been committing offenses since he was a teenager, according to testimony Monday during the punishment phase of his trial.

Steven Lawayne Nelson, 25, is facing the death penalty or life in prison without parole for the suffocation death of the Rev. Clint Dobson at Arlington’s NorthPointe Baptist Church in March 2011. Nelson also beat the church secretary before stealing her car and other items.

Jurors in Fort Worth deliberated a little more than an hour earlier Monday before finding Nelson guilty of capital murder. Prosecutor Page Simpson said during closing arguments that Nelson forced Dobson and his secretary, Judy Elliott, to tie each other up. Simpson called Nelson a “predator” who committed a terrible crime because he wanted to steal a car and the victims’ credit cards.

Nelson had denied killing the minister, saying two friends committed the crime while he stayed outside, and he only entered the church to steal a laptop.

During the penalty phase of his trial, Tarrant County juvenile services intake supervisor Mary Kelleher said Nelson was 14 when he was sent to a juvenile prison for unauthorized use of a motor vehicle and burglary. She said the judge chose the most serious punishment because Nelson had not responded to court-ordered probation and rehabilitation programs.

Kelleher said she liked Nelson, and when she asked him about his behavior, he told her he was bored.

Defense attorneys suggested that Nelson had serious family issues that led to setting his mother’s bed on fire at age 3 and his other intentional attempts at burning down his house at age 6. Kelleher said she did not know about those incidents, apparently documented in reports from Oklahoma, where Nelson and his family lived before moving to Texas.

Several Tarrant County jail guards testified that about a year ago, Nelson broke a jail phone when he became upset after talking to someone. Nelson then cursed, threatened and bumped one guard, and it took three to restrain him, according to testimony. Nelson has been charged with assaulting another jailer in October, which happened about a month later.

Jail guards also testified that during his time in jail before the trial, Nelson broke a light in his cell and destroyed sprinkler heads, and that guards found a shank and narcotics in his cell.